628 research outputs found
Uncovering wall-shear stress dynamics from neural-network enhanced fluid flow measurements
Friction drag from a turbulent fluid moving past or inside an object plays a
crucial role in domains as diverse as transportation, public utility
infrastructure, energy technology, and human health. As a direct measure of the
shear-induced friction forces, an accurate prediction of the wall-shear stress
can contribute to sustainability, conservation of resources, and carbon
neutrality in civil aviation as well as enhanced medical treatment of vascular
diseases and cancer. Despite such importance for our modern society, we still
lack adequate experimental methods to capture the instantaneous wall-shear
stress dynamics. In this contribution, we present a holistic approach that
derives velocity and wall-shear stress fields with impressive spatial and
temporal resolution from flow measurements using a deep optical flow estimator
with physical knowledge. The validity and physical correctness of the derived
flow quantities is demonstrated with synthetic and real-world experimental data
covering a range of relevant fluid flows
Deep Learning of Causal Structures in High Dimensions
Recent years have seen rapid progress at the intersection between causality
and machine learning. Motivated by scientific applications involving
high-dimensional data, in particular in biomedicine, we propose a deep neural
architecture for learning causal relationships between variables from a
combination of empirical data and prior causal knowledge. We combine
convolutional and graph neural networks within a causal risk framework to
provide a flexible and scalable approach. Empirical results include linear and
nonlinear simulations (where the underlying causal structures are known and can
be directly compared against), as well as a real biological example where the
models are applied to high-dimensional molecular data and their output compared
against entirely unseen validation experiments. These results demonstrate the
feasibility of using deep learning approaches to learn causal networks in
large-scale problems spanning thousands of variables
Real-time simulations of transmon systems with time-dependent Hamiltonian models
In this thesis we study aspects of Hamiltonian models which can affect the
time evolution of transmon systems. We model the time evolution of various
systems as a unitary real-time process by numerically solving the
time-dependent Schr\"odinger equation (TDSE). We denote the corresponding
computer models as non-ideal gate-based quantum computer (NIGQC) models since
transmons are usually used as transmon qubits in superconducting prototype
gate-based quantum computers (PGQCs).We first review the ideal gate-based
quantum computer (IGQC) model and provide a distinction between the IGQC, PGQCs
and the NIGQC models we consider in this thesis. Then, we derive the circuit
Hamiltonians which generate the dynamics of fixed-frequency and flux-tunable
transmons. Furthermore, we also provide clear and concise derivations of
effective Hamiltonians for both types of transmons. We use the circuit and
effective Hamiltonians we derived to define two many-particle Hamiltonians,
namely a circuit and an associated effective Hamiltonian. The interactions
between the different subsystems are modelled as dipole-dipole interactions.
Next, we develop two product-formula algorithms which solve the TDSE for the
Hamiltonians we defined. Afterwards, we use these algorithms to investigate how
various frequently applied assumptions affect the time evolution of transmon
systems modelled with the many-particle effective Hamiltonian when a control
pulse is applied. Here we also compare the time evolutions generated by the
effective and circuit Hamiltonian. We find that the assumptions we investigate
can substantially affect the time evolution of the probability amplitudes we
model. Next, we investigate how susceptible gate-error quantifiers are to
assumptions which make up the NIGQC model. We find that the assumptions we
consider clearly affect gate-error quantifiers like the diamond distance and
the average infidelity.Comment: Dissertation, 203 pages, RWTH Aachen University, 2023. This
dissertation includes and extends the results of arXiv:2201.02402 and
arXiv:2211.1101
It Should Not Be Left to Chance: Ensuring a Good Education For All Our Children
This essay suggests that progressive education is equivalent to good education. Condliffe Lagemann poses the question: What do we need to do to ensure that good education becomes more universally available than it is today? The answer lies in developing a new science of education, one that better integrates research, practice, and policy, and does a better job of educating the public about education
The Impact of Agricultural Research in Tropical Africa: A Study of the Collaboration between the International and National Research Systems
CGIAR Study Paper on the problems and opportunities of international agricultural research in Sub Saharan Africa, and the impact of CGIAR Centers on African national agricultural research systems and on agricultural production and food security in Africa. Written by Hans E. Jahnke, Dieter Kirschke, and Johannes Lagermann and published as CGIAR Study Paper No. 21, part of the series comprising the CGIAR Impact Study of the 1980s
Strukturpolitik im Wandel: Wachstumsziel stÀrker gewichtet
Mit der neuen Förderperiode 2007 bis 2013 fĂŒr die EU-Strukturfonds wird der Gestaltungsspielraum der Politik vergröĂert. Welche Förderinstrumente der EU-Strukturpolitik gibt es und wie funktionieren sie? Wie sind die Wirkungen der strukturpolitischen FördermaĂnahmen zu beurteilen? Welche Anforderungen sind an âechteâ Cluster zu stellen? --
Evaluierung einer Wahrnehmungsschwelle von Kameratrackingfehlern beim Compositing realer und virtueller S3D-Videos
Dieses Paper prĂ€sentiert eine Studie zur Untersuchung der Akzeptanz von Kameratrackingfehlern in stereoskopischen Videosequenzen fĂŒr den Einsatz in der Stereo-3D (S3D) Fernsehproduktion. Die klassische Betrachtungsweise von Fehlertoleranzen beim Kameratracking ist rein technisch motiviert. Im Zentrum dieser Studie wird deshalb aus zuschauerzentrierter Sicht die Fragestellung untersucht, ab welcher AusprĂ€gung Trackingfehler in den sechs Freiheitsgraden der extrinsischen Orientierung der Kamera wahrgenommen, beziehungsweise als störend eingeschĂ€tzt werden. Dies geschieht unter Anwendung einer Variation der Methode der eben merklichen Unterschiede (Method of Limits). Die Auswertung zeigt, dass Unterschiede zwischen den einzelnen Parametern existieren und dass das subjektive Empfinden von Trackingfehlern weitaus toleranter ist als die harten rechnerischen Grenzen
A âguerra fiscal dos portosâ e a Resolução 13/12 do Senado Federal: abrangĂȘncia, efeitos e perspectivas.
RESUMO
Esse artigo descreve o contexto em que foi gestada a Resolução 13/12 do Senado Federal com vigĂȘncia a partir de 1Âș de janeiro de 2013 que objetiva enfrentar a guerra fiscal no ICMS entre os estados brasileiros no que concerne Ă importação de bens e mercadorias e aumentar a capacidade competitiva da produção nacional. Registra o esforço da administração tributĂĄria em implantar a medida de unificação em 4% da alĂquota interestadual dos produtos importados de forma a permitir o controle dos fluxos comerciais de produtos industriais elaborados com insumos importados. E conclui a respeito da natureza da medida, classificando-a como uma solução parcial para a guerra fiscal dos portos, em consonĂąncia com a proposta de reforma tributĂĄria formulada pelo governo federal para o ICMS. Um dos efeitos imediatos foi a redistribuição da receita do ICMS relativa Ă importação entre os estados, em detrimento dos que utilizaram esse instrumento para atrair empreendimentos, principalmente de atacadistas. Mas o processo estĂĄ em andamento e novas acomodaçÔes deverĂŁo ocorrer, criando a expectativa a respeito da mudança de fluxos comerciais e de relocalização de empresas.
Palavras-chave: ICMS; guerra fiscal; Resolução 13/12 do Senado Federal
TĂTULO EM INGLĂS
âHarbors fiscal warsâ and the 13/12 Senate Resolution: scope, effects and
perspectives.
ABSTRACT
This article describes the context in which was conceived the Resolution 13/12 of the Brazilian Federal Senate, effective from January 1, 2013. That Resolution aimed to tackle the tax incentives competition between the Brazilian States involving the Tax on the Circulation of Commodities and Services (ICMS) with regard to the importation of goods and commodities, as well as to increase the competitive capacity of the national production. The paper registers the effort of tax administration authorities in deploying measures to unify in 4% the interstate rate on imported products, in order to allow the control of trade flows of industrial products made with imported raw materials. It concludes by analyzing the nature of that initiative, classifying it as a partial solution to the âports fiscal warâ, being in accordance with the tax reform proposal formulated by the Federal Government regarding the ICMS. One of its immediate effects was the redistribution of revenues of ICMS on imports between Member States, to the detriment of those who used this instrument to attract businesses, mainly of wholesalers. But the process is still underway, and new accommodations are likely to occur, creating the expectation of changes in trade patterns, as well as of business relocations.
Key words: ICMS; tax competition; Resolution 13/12 of the Brazilian Federal Senate
Artigo recebido em 23 set. 2013
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